The disclosures herein relate to a distal femoral osteotomy system and method, and, more particularly, to a system and method for correcting for leg bone malalignment using distal femoral osteotomy.
Malalignment of the anatomical axis and the mechanical axis of a leg bone along the tibia and the femur in the coronal plane leads to several problems, including tibial-femoral varus and valgus, and degenerative osteoarthritis of the knee. Previous attempts to correct for this have included an upper tibia osteotomy, according to which a wedge-shaped segment is cut from the upper end portion of the tibia bone. After the segment is removed, an external compressor device is fastened to the bone and draws the osteotomy closed by plastic deformation of the unsevered portion of the bone. The realigned bone portions are then secured by a plate using screw fixation. Examples of this technique are disclosed in U.S. Pat. No. 5,021,056 and U.S. Pat. No. 5, 053,039, assigned to the assignee of the present invention, and their disclosures are incorporated by reference.
In U.S. Pat. No. 5,613,969, a surgical kit for performing a tibial osteotomy is provided, comprising a pair of mounting pins for attaching an osteotomy guide in a predetermined relation to a tibia, an osteotomy guide comprising a transverse slot defining a transverse cutting plane adapted to receive and guide a transverse cutting blade for making a transverse cut into the tibia, and a plurality of oblique slots angularly offset from the transverse slot, each oblique slot defining an oblique cutting plane adapted to receive and guide an oblique cutting blade for making a selected oblique cut into the tibia, wherein the intersection of each oblique cutting plane with the transverse cutting plane defines a wedge of bone which may be removed from the tibia. Also included with the surgical kit are a compression clamp adapted to apply compressive forces to a first portion of the tibia above the transverse cut and to a second portion of the tibia below the oblique cut to draw the first and second portions together, and a fixation plate adapted to hold the portions of the tibia together during healing.
Although this type of procedure considerably advanced the art for correcting for leg malalignment by tibia osteotomy, it is recognized that certain malalignment in lateral compartment osteoarthritis is best managed by osteotomy on the distal femur. However, there are several disadvantages to the lafter procedure. For example, there is often a mismatching of osteotomy surfaces and a consequent mismatching of cortical margins, providing less stable surfaces to compress against one another. Additionally, the distance of the osteotomy away from the deformity apex creates an additional relative lateral translation of the distal fragment. Thus, the osteotomy must be completed, rather than hinged, on the lateral side, therefore creating an unstable osteotomy. As a result, a plate on the medial side cannot be utilized as in the case of an upper tibial osteotomy. Also, these distal femoral osteotomies often suffer from the fact that they are difficult to reproduce and therefore unpredictable.